1. Technological Field
The present invention relates to a transmission system, a signal receiver, a test apparatus and a test head. More specifically, the invention relates to a transmission system, a signal receiver, a test apparatus and a test head for transmitting a transmission signal.
2. Background Art
Conventionally, there has been known a signal transmission method for transmitting a signal in synchronism with a clock outputted from a PLL (Phase Locked Loop) as disclosed, for example, in Japanese Patent Application Publication (Laid-Open) No. 2000-13218 (in particular FIG. 1) and Japanese Patent Application Publication (Laid-Open) No. 2002-198940 (in particular FIG. 1). The PLL has a VCO (Voltage Controlled Oscillator) and oscillates the VCO with predetermined frequency by applying voltage based on a phase difference between an output of the reference oscillator and an output of the VCO to output an output of the VCO to the outside as an output clock.
However, the output clock of the PLL contains random jitter caused by phase noise of the VCO. Therefore, there has been a case when an error occurs in transmitting a signal by using the clock outputted from the PLL due to the random jitter for example.
Accordingly, it is an object of the invention to provide a transmission system, a signal receiver, a test apparatus and a test head capable of solving the above-mentioned problem. This object may be achieved through the combination of features described in independent claims of the invention. Dependent claims thereof specify preferable embodiments of the invention.